X x x e electbicai ihdicatiug instrtjmbitt



I I May 927 J. R. BARNHART ELECTRICAL INDICATING INSTRUMENT I FiledMarch 1-922 Patented May 31, 1927.

JOB'R. BAn'itHAnno LAKnWoon, (Q1110, Assieivon To wAnrnnivrxsoori",batman QELECTRIGAL innioe'rrne'insrnnnnnr.

Application filed March 8, 1922 Serial no. 542,175.

production, and highly ,eiiicient in operation.

Another object of the invention is to providev an'instrument of thischaracter wh ch jshall be of the same general construction as a directcurrent voltmeter or amm'eter but which shall be capable of deflectingthe indicator in the same direction each time an alternating current sapplied there to.-.... A, still further object is to provideaninstrument of this character which shall be so constructed and arrangedas to have'a "Q11 substantially uniform scale and which shall beaoourateover a wide range of voltages or'amperages;

' With these and other objects in View, the

invention. resides in thevarious novel fea'. tures of construction andarrangement or combination of parts, allof which will be fullydescribed. hereinafter and pointed out in the appended claims; I y V Inthe accompanying draw1ngs, E1g.-' 1

is a front elevation of an 'alternatingcurrent voltmeter or ammeter'con'structed'in accord ance with-my invention;- ,Fig. 2 is a rearelevation, andFig. 3 a side elevation re-- spectively, with the housingremoved; Figs.

4 and 5 are sectional views taken respec-- tively on the'line 47-4: and55 of Fig. 3; Fig. 6 is a detail perspectlve Vl'eW of the solenoid, withparts broken away; and Flg.

7 a sectional-view of a modified form ofvoltg V I Wlll, exert a forceonthe armaturefi'whioh 3' meter or ammeter;

Describing by reference characters the va rious parts illustrated, 1denotes a suitable base which is provided on one SlClG Wlth a scale 2-andon the opposite side with a permanent magnet 3 which is convenientlysecured thereto by clips 4 struck up from said base. A needle staff 5 isarranged between the poles of magnet 3 and is pivotally sup portedbetween the base and an upper sup porting member 7 which projectslaterally from a pair of legs 6; The staff 5 has mounted thereon anarmature 9, an-indicating needle 10, and a damping device 11,

said damping device being located in or.

adjacent to a point ofhigh concentration "of the permanent magnet fieldwhich tends to resist rapid and vibratorylmovement'ofthe,indlcatnmgneedle, and the armature: 9

located or adjacent to the fieldfofgasole-g noid, to be referredtohereinafter.

Agbridge 14 having downwardly and 3111- Y wardly projecting lugs 15 issecured to'the.

base in any. suitable manner, as by, means of screws. 16. This bridge isprovided on underside Wltli an apron 17 dfill'lsllldlllng.

material, and is clamped'to the bridge by' binding posts 18, 18. Thesebinding posts- ,extend through enlarged apertures inxthe bridge, 'andare insulated from. the bridge by said apron and byiisuitableinsulatingl .washers19. p

2O denotes a solenoid, which is wound on f. ahollow sheetmetal form21,preferablyof non magnetic.material, suchas brass. This '[form isrectangular in. cross section and one end thereof is projected beyondthe winding 20, as indicated at 22, and bent upon itself 5 about theinsulatingf'apron 17 to whichit i is adjustably fastened; by a screw [Inpractice a' sheet of soft iron 2451s positioned; along onefof thelateraledges of thejwind' ing form, as shown in Fig. 6, thena sheet of insulatng material 2 5 'is placed about. the 1 winding 'form and sheetiron, 5.0that the solenoid'gwindingwill be insulated from the metal parts.:Theends 'ofthe solenoid wind-I ing are connected to theirrespectivebinding posts18, 18. Y V V The base 1 and associatedpartsareasdling thereof. 7

will tend to -;normally retain. the indicating .90, sembledlinajsuitable cup-shaped casing 26 .1 to protect the meter and facilitatethe; ban

needle 10 at'zero po'sition. {When an alter- 5 nating current is appliedto; theterminals 18, 18., the solenoid will be energizedanda magneticfield created thereabout. [The magnetic .linesof force of this fieldwill pass 7 through the softir'on 24: and hence cause ahigherjconcentration of these lines of force "on one sideof the solenoidthan elsewhere.

This concentrated magnetic field will alwaysexert'a stronger nitial pullon the corresponding side of the armature 9'and hence cause 'thearmature and the staff and the elements associated therewith to berotated in thesame predetermined direction each that'the influenceexerted-by it on the armaa position of the soft iron 24 with respect tothe armature 9 as shown in Fig. is :such

-ture is greatest when the armature stands *approxlmatelyln its originalposltion or just before it beginsto respond to the magnetic attractionand rapidly decreases as the end "of the armature is draw-nwithin ortowardthe solenoid, thus making possible a substantially uniform scalecalibration for amineter, the COIIlblIlZItlOIl, with a soleno d,-

the indicating needle.

In Fig. 7 I have shown a nodified form- [of construction for imparting apredeten 7 rent.

mined initial direction of rotation to the armatureand indicating needlewhen the SOlQIlOlfl isenergizedby an alternating cur"- In, this form, anarmature isprO- ivided with oppositely projecting ends 31' one of theseends projecting toward the solenoid 32jand the opposite end projecting Iexerted onxthe other side thereof-L mv an opposite direction therefrom,The perm anent magnet 33 is so arranged that the influence of its magnetic field on the armature 30 will tend to retain the needle at zeroposition; When the solenoid 321's en-.

ergized byan alternating curren't,the needle staff will, always'bedeflected in a counterclockwise direction, as "viewed in Fig. since oneend of the armature 3O1snearerthe magnetic field of the solenoid thanthe parted to the needle staff, irrespective of the other end, and hencea rotational movement in a; predetermined direction will" be imdirectionof the current flowing through the solenoid; The remaining elements ofthe meter are snnllar to those previously de- COIHiQCtlOlI' with Figs;1-6 'lIl Clu- 1 scribed in s1ve..

I claim is: r I

1. In an alternatlng current voltmeter or ammeter, the combination, witha solenoid,

'' Having thus described my invention, what of a movable system mounted'inoperative relation to said solenoid, an armature. car

riedby said movable system and arranged nearer one pole of said solenoidtha'n' the, other, said armature being adapted to be attracted by saidsolenoid, and means posi ti'on'ed along one side of saidsolenoidterausing a higher co ncentration of the mag amineter, thecombinatiomwith a solenoid,

of a movable system mounted in operative relation to said solenoid,anjarmature carried by said-' movable system and arranged nearer onepole'of said solenoid than "theother, said-' armature :being adapted tobe attracted by said solenoid, and means for causing a higherconcentration of the magnetic field on one 'sideofsa-id'solenoid than onthe other side. a 3. In an alternating current voltmeter or of movablesysteminounted' in operative relation to said solenoid, an armaturecar-fried by said movable s'yste-ni and arranged" nearer one, pole ofsaid'solenoid than the other, said armature being adapted to beattracted by said solenoid, and a soft iron ore positioned along oneofthe lateral edges of-said solenoid"ad'aptedto increase the-pullotfsuchside on said armature over; the pull 4Q Inan alternating currentvoltmeter; or annn'et'er, the COmblIlatlOn, with' a bas'eof a permanentmagnet carried by said base, a f

movable system mounted in: operative relm tionto saidn'iagnet, a dampingdevice'bari of: a movable system mounted outside of? and adjacent to onepole ofsaid solenoid,=an-

armature" carried by said movable system adapted to be attracted-bysaid'solenoid,a soft iron element arranged on one side of" said solenoidfor increasingthe pull "ofsuchside upon *said armature" over the" pulleX-- ertedrby the other side thereof and -a damping device carried bysaidim'ova'ble system ;In testimony whereof, I hereunto aflix'mysignature. I

I .1013 it BAR-NHABT.

